Gastrointestinal health is a major concern of consumers in both developed and developing countries from the point of view of daily gastrointestinal comfort and also resistance to or prevention of acute and chronic diseases such as infectious diarrhoea and inflammatory bowel diseases. There is a demand for products that can be consumed on a daily basis that can provide such benefits.
Currently available strategies to address these concerns include probiotic products wherein liquids (typically dairy-based drinks) containing one or a number of strains of beneficial bacteria are consumed to derive a benefit such as improved gut health and/or improved natural defences. This approach is limited since it requires the products to be chilled (to maintain viability of the bacteria that provide the benefit), and questions remain over its efficacy since the bacteria must pass through the harsh acidic environment of the stomach and reach the colon in sufficient numbers to provide the intended effects. Furthermore, such considerations mean that probiotic products are typically expensive for the consumer and require a complex supply chain to effectively deliver them.
An alternative strategy is the use of prebiotics wherein food components are given that have a beneficial health effect through their selective metabolism in the intestinal tract. Typical targets for such an approach are bifidobacteria and lactobacilli (i.e. common probiotic species) since they are generally regarded as safe, are commonly found in breast fed infants in high numbers, alter the intestinal environment through the production of short chain fatty acids meaning that pathogens cannot colonise, produce antimicrobial components that target pathogens, may improve the immune status of the host and may reduce inflammation of the colon associated with poor modem diets. Currently available prebiotics include fructans such as inulin and fructo-oligosaccharides and these have been shown to significantly increase bifidobacteria in humans.
Prebiotics do not suffer from questions over their viability in the way probiotics do and they can be formulated into a number of product formats without loss of viability. However, in certain aspects, current prebiolics are difficult to formulate into common foodstuffs owing to their impact on product taste (fructans can be slightly sweet) and structure (they can change mouthfeel). Furthermore, products are often required to be formulated with higher than the effective amount of prebiotic owing to the fact that fructans can suffer degradation during pasteurisation, baking, sterilisation and similar processes. These considerations mean that prebiotic-containing processed food products remain expensive and thus limited to only a small number of customers because of price.
Thus a demand exists from consumers for an affordable solution wherein benefits can be provided in the arena of gut health, resistance to infectious diseases and/or prevention of chronic gastrointestinal diseases.
Tea has been consumed in one form or another for over 4000 years and is now popular in both developed and developing countries. Tea is popular for a number of reasons: it is generally regarded as healthy, it can be a safe alternative to untreated water and is associated with benefits such as relaxation, mental alertness and has a widely acceptable taste. The low price of tea also means that it can be consumed by consumers in all socio-economic groups.
Several documents suggest that consumption of black tea and/or components thereof can have positive effects on the health of the consumer. For example, US 2008/119545 A and US 2008/075795 A (both in the name of C. HENSLEY & S. PYO) disclose methods and compositions for preventing and treating Avian Influenza utilizing an effective quantity of an ingredient having a composition selected from the group consisting of theaflavin, theaflavin-3,3′-digallate, theaflavin-3-monogallate, theaflavin-3 gallate, theaflavin-3′-gallate, thearubigin, gallic acid, tannic acid, (−)-epigallocatechin gallate (EGCG), (−) epigallocatechin (EGC), (+)-epicatechin (EC), (−)-gallocatechin gallate (GCG), and catechin.
It has also been suggested that black tea and/or components thereof can have positive effects on gut function and/or health. For example, K. Jafari et al (Medical Hypotheses, 2006, 67(2), p. 419) discloses that black tea extract and its major polyphenolic pigment may ameliorate the gastrointestinal disorder in irritable bowel syndrome; and L. Chaudhuri et al (Life Sciences, 2000, 66(9), pp. 847-854) discloses that a hot water extract of black tea significantly accelerated the gastrointestinal transit (GIT) in vivo in mice.
Compositions comprising black tea components in combination with conventional prebiotics are also known. For example, WO 2007/056432 A (PERQUE INC) discloses compositions comprising one or more prebiotics (e.g., one or more dietary fibers) in combination with selenium compounds, flavonoids and/or flavonols, and phosphatides; and US 2008/085349 A (Z. Y. CHEN) discloses a beverage comprising tea components and a non-digestible health sweetener (VitaSugar® IMO).
It has also been recognised that black tea and/or components thereof can have a positive influence on gut microflora.
U.S. Pat. No. 5,071,653 (ITOEN LTD) discloses substantially flavorless extracts from the leaves of C. sinensis which promote the growth of bifidobacteria. The compositions are provided by extracting water or ethanol-soluble solids from C. sinensis leaves with a polar organic solvent that is immiscible with water. There is no evidence in U.S. Pat. No. 5,071,653 that the extracts disclosed therein have a true prebiotic effect (i.e. that promotion of the growth of bifidobacteria is in preference to promotion of the growth of pathogenic bacteria such as clostridia). Furthermore, the extracts disclosed therein are substantially flavourless and thus are presumably devoid of the flavonoids (such as thearubigin) which give black tea its distinctive taste.
WO 2004/056205 A (UNILEVER) discloses the use of a cooked food product comprising black tea leaves, an extract of black tea or a mixture thereof, to maintain or improve microflora balance and/or to treat or prevent diarrhoea in a subject consuming the composition and wherein the black tea leaves or the extract of black tea is/are present in an unbound state.
We have now found that the flavonoid components of black tea have a significant prebiotic effect. Furthermore we have identified that black tea flavonoids having a specific composition are especially effective prebiotics and thus may be expected to be especially effective at delivering the health benefits associated with consumption of prebiotics, such as treatment or prevention of a gastrointestinal condition, and/or treatment or prevention of a condition associated with sub-optimal immunity. We have also found that these black tea flavonoids have improved immunomodulatory capability compared to whole tea extracts.